This study compared a novel non-formaldehyde combination product developed for pathogen control in animal feed Finio (A), with a panel of three commonly used organic acid feed additive products: Fysal (B), SalCURB K2 (C) and Salgard (D). Products were evaluated for their ability to reduce Salmonella Typhimurium DT104 and avian pathogenic Escherichia coli in poultry feed. A commercial layer-hen mash was treated with each product and then mixed with feed previously contaminated (via inoculated meat and bone meal) with either Salmonella or E. coli. After 24 h at room temperature, 10 replicate samples were taken from each preparation and plate counts were performed using a selective agar. All concentrations of product A (0.5, 1.0, 1.5, 2.0 and 2.5 kg per metric tonne (MT)) plus the higher concentration of products B and D (6.0 kg MT⁻¹) significantly reduced Salmonella counts compared with those in the untreated control group (p < 0.05). Product C did not significantly reduce levels of Salmonella under these conditions. Because of the poor recovery of E. coli, statistical comparisons for this organism were limited in scope, but only product A at the highest concentration appeared to have eliminated it.

In a recent study, the pH of commonly used Salmonella pre-enrichment media became acidic (pH 4.0 to 5.0) when feed or feed ingredients were incubated for 24 h. Acidic conditions have been reported to injure or kill Salmonella. In this study, cultures of four known feed isolates (S. montevideo, S. senftenberg, S. tennessee, and S. schwarzengrund) and four important processing plant isolates (S. typhimurium, S. enteritidis, S. infantis, and S. heidelberg) were grown on meat and bone meal and later subjected to desiccation and heat exposure to stress the microorganism. The impact of stress on the isolates ability to survive in acidic conditions ranging from pH 4.0 to 7.0 was compared to the non-stressed isolate. Cell injury was determined on xylose lysine tergitol 4 (XLT4) and cell death determined on nutrient agar (NA). When measured by cell death in non-stressed Salmonella, S. typhimurium was the most acid tolerant and S. heidelberg was the most acid sensitive whereas in stressed Salmonella, S. senftenberg was the most acid tolerant and S. tennessee was the most acid sensitive. The pH required to cause cell injury varied among isolates. With some isolates, the pH required for 50% cell death and 50% cell injury was similar. In other isolates, cell injury occurred at a more neutral pH. These findings suggest that the pH of pre-enrichment media may influence the recovery and bias the serotype of Salmonella recovered from feed during pre-enrichment.

SUMMARY Three studies were conducted using Clostridium perfringens as an intestinal challenge to produce necrotic enteritis (NE). The studies consisted of two battery screening studies and one production study in floor pens. The purpose of the trials was to determine if reducing the level of microorganisms in feed consumed by broilers reduced the impact of a nonfeed-based Clostridial challenge. In all studies, C. perfringens challenged broilers consuming feed containing lower levels of microorganisms compared to control feed exhibited significantly (P < 0.05) better feed conversion (feed conversion was improved by 14% in battery trials and by 4.2% in the pen trial) than did C. perfringens-challenged broilers consuming control feed. In battery trials, body weight gain and NE-associated mortality were also significantly improved in C. perfringens-challenged broilers consuming feed containing lower levels of microorganisms (16.5% improvement in body weight gain and 72.5% reduction in NE-associated mortality)... RESUMEN Impacto del control bacteriano de los alimentos sobre el desempeño de pollos de engorde durante un desafío por Clostridium Se condujeron tres estudios utilizando Clostridium perfringens como un desafío intestinal para producir enteritis necrótica. Los estudios consistieron en dos ensayos de selección en baterías y un estudio de producción dentro corrales en piso. El propósito de los ensayos fue determinar si la reducción del nivel de microorganismos en el alimento consumido por pollos de engorde redujo el impacto de un desafío por Clostridium mediante una ruta diferente de la alimentaria. En todos los estudios, los pollos de engorde desafiados con C. perfringens que consumían alimentos con niveles más bajos de microorganismos en comparación con los alimentos control exhibieron significativamente una mejor conversión alimenticia (P <0.05) (la conversión alimenticia fue mejorada en un 14% en ensayos en baterías y en un 4.2% en el ensayo en piso) que los pollos de engorde desafiados con C. perfringen...

SUMMARY. The ability of pre-enrichment media to buffer pH changes that occur during incubation is essential for recovery and detection of Salmonella from feed/

Studies were conducted to investigate the recovery of Campylobacter from feed. The impact of feed moisture, water activity, pH, number of background microflora and the use of different antibiotic supplements in Campylobacter enrichment broth (CEB) on Campylobacter recovery were evaluated in five studies. Broiler starter feed was inoculated with 10(4) -10(5) cfu of Campylobacter/g and stored at 24 degrees C and 43% RH. Enrichment culture was conducted on the day of inoculation or 24 h post inoculation and every 48 h of storage thereafter for 14 d. Feed moisture, water activity, pH and level of background microflora were not correlated with Campylobacter recovery. The incubation of feed in CEB with no antibiotic supplement resulted in the number of background microflora increasing to 10(9) cfu/g and the pH of the media decreasing to pH 4-5 impacting recovery. Addition of certain antimicrobial supplements to CEB reduced background microflora growth and maintained a near neutral pH. Campylobacter was recovered up to 10 days post inoculation when using CEB containing antibiotic supplements compared to 1 day in CEB. These findings suggest that Campylobacter can be recovered from feed and the type of antimicrobial supplement utilized influences recovery by controlling extraneous microbial growth which occurs during enrichment.